GraphQL Object Types and Fields

1. Introduction

GraphQL is a query language for APIs and a runtime for executing those queries by using a type system you define for your data. This lesson focuses on Object Types and Fields, which are fundamental building blocks in GraphQL schema design.

2. Object Types

An Object Type in GraphQL is a collection of fields that define the data structure. Each field can return a scalar type or another object type.

2.1 Definition

Object types are defined in the GraphQL schema language as follows:

type User {
    id: ID!
    name: String!
    email: String
}

In this example, the User type has three fields: id, name, and email.

2.2 Key Takeaways

• Each field in an Object Type has a type, which can be a scalar or another Object Type.
• Fields can be mandatory (non-nullable) or optional.

3. Fields

Fields are the individual components of an Object Type. Each field has a name and a type. You can also define arguments for fields, which allow for more flexible queries.

3.1 Defining Fields

Fields are defined in the same way as Object Types. Here's an example of fields with arguments:

type Post {
    id: ID!
    title: String!
    author: User!
    comments(limit: Int, offset: Int): [Comment]
}

In this example, the comments field takes two arguments: limit and offset, and returns a list of Comment objects.

3.2 Field Types

• Scalar Types: Basic data types like String, Int, Float, Boolean, ID.
• Object Types: Defined types that can have their own fields.
• Lists: Defined with brackets, e.g., [User].

4. Best Practices

When designing Object Types and fields, consider the following best practices:

• Use meaningful names for Object Types and fields.
• Keep your schema as flat as possible to avoid complexity.
• Document your schema with descriptions for better understanding.
• Utilize non-nullable types to enforce data integrity.

5. FAQ